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Abstract

Background: Identifying the mechanism of supraventricular tachycardia (SVT) can often be challenging. We investigated the role of simultaneous atrial and ventricular (A+V) pacing in discriminating between atrial (AT), atrioventricular nodal reentrant (AVNRT), and orthodromic reciprocating (ORT) tachycardias.

Methods: Patients undergoing electrophysiological testing or ablation of SVT were included. The response of tachycardias to A+V pacing at 80% to 90% of the tachycardia cycle length (CL) was recorded. The truth of the SVT was ascertained though established pacing maneuvers and successful ablation of the SVT mechanism.

Results: A total of 80 patients (age=48±17 years; 43 men; ejection fraction=57±8%) were included. Of those, 10 patients had AT, 24 had AVNRT, and 23 had ORT. Another 24 patients underwent procedures for other arrhythmias. As shown in the table, in response to A+V pacing, SVT termination was documented in 18 of 64 (28%) AT, in 57 of 147 (39%) AVNRT, and in 93 of 108 (86%) ORT episodes. After cessation of A+V pacing, the first recorded electrogram was atrial (A) in all 46 persisting AT episodes, a His bundle (H) in all 86 persisting AVNRT episodes, and mixed (A in 7, His in 5, and ventricular in 3) in the 15 persisting ORT episodes. An additional 290 sinus tachycardia (ST) episodes in 49 patients also exhibited an A response similar to AT episodes.

Conclusions: The first return intracardiac signal after simultaneous A+V pacing is A in AT or ST and H in AVNRT. This new maneuver which does not depend on the ability to entrain the SVT with ventricular pacing completely separates between AT and AVNRT and can therefore be added to the armamentarium of maneuvers used in the electrophysiology laboratory.